Synthesis of Oxorhenium(V) Complexes Derived from 7α-Functionalized Testosterone: First Rhenium-Containing Testosterone Derivatives

In an effort to assist in the preparation of metal-containing ligands for the androgen receptor, we have synthesized the first oxorhenium(V) complexes containing a pendant testosterone moiety. The key step in the synthesis involves the copper-catalysed, α-selective 1,6-Michael addition of a 4-pentenylmagnesium bromide to 6-dehydrotestosterone 17β-acetate. The α-stereoselectivity is governed by the presence of the C-19 methyl group. The absolute configurations of the epimers were investigated by 1H-NMR studies. Further chemical transformations of the 7α-pentenyl spacer introduced the terminal thiol group, needed for complex formation. The complex formation was accomplished by the “3+1” mixed-ligand concept using two different rhenium precursors. The obtained complexes differ with respect to the central donor atom of the tridentate ligand part, namely, S and O.